diff --git a/tests/cache_check.rs b/tests/cache_check.rs
index f89c182..6b6b668 100644
--- a/tests/cache_check.rs
+++ b/tests/cache_check.rs
@@ -29,8 +29,8 @@ impl<'a> Program<'a> for CacheCheck {
         "cache_check"
     }
 
-    fn path() -> &'a str {
-        CACHE_CHECK
+    fn path() -> &'a std::ffi::OsStr {
+        CACHE_CHECK.as_ref()
     }
 
     fn usage() -> &'a str {
diff --git a/tests/cache_dump.rs b/tests/cache_dump.rs
index a8f3754..365d69b 100644
--- a/tests/cache_dump.rs
+++ b/tests/cache_dump.rs
@@ -25,8 +25,8 @@ impl<'a> Program<'a> for CacheDump {
         "cache_dump"
     }
 
-    fn path() -> &'a str {
-        CACHE_DUMP
+    fn path() -> &'a std::ffi::OsStr {
+        CACHE_DUMP.as_ref()
     }
 
     fn usage() -> &'a str {
diff --git a/tests/common/input_arg.rs b/tests/common/input_arg.rs
index 4e096db..20feac4 100644
--- a/tests/common/input_arg.rs
+++ b/tests/common/input_arg.rs
@@ -53,7 +53,8 @@ pub fn test_missing_input_arg<'a, P>() -> Result<()>
 where
     P: InputProgram<'a>,
 {
-    let stderr = run_fail(P::path(), &[])?;
+    let args: [&str; 0] = [];
+    let stderr = run_fail(P::path(), &args)?;
     assert!(stderr.contains(P::missing_input_arg()));
     Ok(())
 }
diff --git a/tests/common/mod.rs b/tests/common/mod.rs
index a4801aa..e9dffd8 100644
--- a/tests/common/mod.rs
+++ b/tests/common/mod.rs
@@ -1,9 +1,11 @@
 #![allow(dead_code)]
 
 use anyhow::Result;
+use std::ffi::{OsStr, OsString};
 use std::fs::OpenOptions;
 use std::io::{Read, Write};
 use std::path::PathBuf;
+
 use thinp::file_utils;
 use thinp::io_engine::*;
 
@@ -104,7 +106,7 @@ pub enum ArgType {
 
 pub trait Program<'a> {
     fn name() -> &'a str;
-    fn path() -> &'a str;
+    fn path() -> &'a OsStr;
     fn usage() -> &'a str;
     fn arg_type() -> ArgType;
 
@@ -134,8 +136,15 @@ pub trait BinaryOutputProgram<'a>: OutputProgram<'a> {}
 //------------------------------------------
 
 // Returns stdout. The command must return zero.
-pub fn run_ok(program: &str, args: &[&str]) -> Result<String> {
-    let command = duct::cmd(program, args).stdout_capture().stderr_capture();
+pub fn run_ok<S, I>(program: S, args: I) -> Result<String>
+where
+    S: AsRef<OsStr>,
+    I: IntoIterator,
+    I::Item: Into<OsString>,
+{
+    let command = duct::cmd(program.as_ref(), args)
+        .stdout_capture()
+        .stderr_capture();
     let output = command.run()?;
     assert!(output.status.success());
     let stdout = std::str::from_utf8(&output.stdout[..])
@@ -146,16 +155,30 @@ pub fn run_ok(program: &str, args: &[&str]) -> Result<String> {
 }
 
 // Returns the entire output. The command must return zero.
-pub fn run_ok_raw(program: &str, args: &[&str]) -> Result<std::process::Output> {
-    let command = duct::cmd(program, args).stdout_capture().stderr_capture();
+pub fn run_ok_raw<S, I>(program: S, args: I) -> Result<std::process::Output>
+where
+    S: AsRef<OsStr>,
+    I: IntoIterator,
+    I::Item: Into<OsString>,
+{
+    let command = duct::cmd(program.as_ref(), args)
+        .stdout_capture()
+        .stderr_capture();
     let output = command.run()?;
     assert!(output.status.success());
     Ok(output)
 }
 
 // Returns stderr, a non zero status must be returned
-pub fn run_fail(program: &str, args: &[&str]) -> Result<String> {
-    let command = duct::cmd(program, args).stdout_capture().stderr_capture();
+pub fn run_fail<S, I>(program: S, args: I) -> Result<String>
+where
+    S: AsRef<OsStr>,
+    I: IntoIterator,
+    I::Item: Into<OsString>,
+{
+    let command = duct::cmd(program.as_ref(), args)
+        .stdout_capture()
+        .stderr_capture();
     let output = command.unchecked().run()?;
     assert!(!output.status.success());
     let stderr = std::str::from_utf8(&output.stderr[..]).unwrap().to_string();
@@ -163,8 +186,15 @@ pub fn run_fail(program: &str, args: &[&str]) -> Result<String> {
 }
 
 // Returns the entire output, a non zero status must be returned
-pub fn run_fail_raw(program: &str, args: &[&str]) -> Result<std::process::Output> {
-    let command = duct::cmd(program, args).stdout_capture().stderr_capture();
+pub fn run_fail_raw<S, I>(program: S, args: I) -> Result<std::process::Output>
+where
+    S: AsRef<OsStr>,
+    I: IntoIterator,
+    I::Item: Into<OsString>,
+{
+    let command = duct::cmd(program.as_ref(), args)
+        .stdout_capture()
+        .stderr_capture();
     let output = command.unchecked().run()?;
     assert!(!output.status.success());
     Ok(output)
diff --git a/tests/thin_check.rs b/tests/thin_check.rs
index 577a34d..bfe1161 100644
--- a/tests/thin_check.rs
+++ b/tests/thin_check.rs
@@ -31,8 +31,8 @@ impl<'a> Program<'a> for ThinCheck {
         "thin_check"
     }
 
-    fn path() -> &'a str {
-        THIN_CHECK
+    fn path() -> &'a std::ffi::OsStr {
+        THIN_CHECK.as_ref()
     }
 
     fn usage() -> &'a str {
diff --git a/tests/thin_delta.rs b/tests/thin_delta.rs
index c9256a8..7455f10 100644
--- a/tests/thin_delta.rs
+++ b/tests/thin_delta.rs
@@ -26,8 +26,8 @@ impl<'a> Program<'a> for ThinDelta {
         "thin_delta"
     }
 
-    fn path() -> &'a str {
-        THIN_DELTA
+    fn path() -> &'a std::ffi::OsStr {
+        THIN_DELTA.as_ref()
     }
 
     fn usage() -> &'a str {
diff --git a/tests/thin_dump.rs b/tests/thin_dump.rs
index 6d6eb11..2f1fae6 100644
--- a/tests/thin_dump.rs
+++ b/tests/thin_dump.rs
@@ -32,8 +32,8 @@ impl<'a> Program<'a> for ThinDump {
         "thin_dump"
     }
 
-    fn path() -> &'a str {
-        THIN_DUMP
+    fn path() -> &'a std::ffi::OsStr {
+        THIN_DUMP.as_ref()
     }
 
     fn usage() -> &'a str {
diff --git a/tests/thin_metadata_pack.rs b/tests/thin_metadata_pack.rs
index 616bc83..bbcb8c0 100644
--- a/tests/thin_metadata_pack.rs
+++ b/tests/thin_metadata_pack.rs
@@ -36,8 +36,8 @@ impl<'a> Program<'a> for ThinMetadataPack {
         "thin_metadata_pack"
     }
 
-    fn path() -> &'a str {
-        THIN_METADATA_PACK
+    fn path() -> &'a std::ffi::OsStr {
+        THIN_METADATA_PACK.as_ref()
     }
 
     fn usage() -> &'a str {
diff --git a/tests/thin_metadata_unpack.rs b/tests/thin_metadata_unpack.rs
index 9a66d58..3702e73 100644
--- a/tests/thin_metadata_unpack.rs
+++ b/tests/thin_metadata_unpack.rs
@@ -36,8 +36,8 @@ impl<'a> Program<'a> for ThinMetadataUnpack {
         "thin_metadata_pack"
     }
 
-    fn path() -> &'a str {
-        THIN_METADATA_UNPACK
+    fn path() -> &'a std::ffi::OsStr {
+        THIN_METADATA_UNPACK.as_ref()
     }
 
     fn usage() -> &'a str {
diff --git a/tests/thin_repair.rs b/tests/thin_repair.rs
index aa2deba..e9b3b92 100644
--- a/tests/thin_repair.rs
+++ b/tests/thin_repair.rs
@@ -29,8 +29,8 @@ impl<'a> Program<'a> for ThinRepair {
         "thin_repair"
     }
 
-    fn path() -> &'a str {
-        THIN_REPAIR
+    fn path() -> &'a std::ffi::OsStr {
+        THIN_REPAIR.as_ref()
     }
 
     fn usage() -> &'a str {
diff --git a/tests/thin_restore.rs b/tests/thin_restore.rs
index 5208d71..7408be0 100644
--- a/tests/thin_restore.rs
+++ b/tests/thin_restore.rs
@@ -30,8 +30,8 @@ impl<'a> Program<'a> for ThinRestore {
         "thin_restore"
     }
 
-    fn path() -> &'a str {
-        THIN_RESTORE
+    fn path() -> &'a std::ffi::OsStr {
+        THIN_RESTORE.as_ref()
     }
 
     fn usage() -> &'a str {
diff --git a/tests/thin_rmap.rs b/tests/thin_rmap.rs
index 1acae99..bdee4cd 100644
--- a/tests/thin_rmap.rs
+++ b/tests/thin_rmap.rs
@@ -26,8 +26,8 @@ impl<'a> Program<'a> for ThinRmap {
         "thin_rmap"
     }
 
-    fn path() -> &'a str {
-        THIN_RMAP
+    fn path() -> &'a std::ffi::OsStr {
+        THIN_RMAP.as_ref()
     }
 
     fn usage() -> &'a str {